/*Problem Id:1003  User Id:team01 
Memory:24K  Time:15MS
Language:C++  Result:Accepted

	problem name: To and Fro
	source : East Central North America 2004 
	problem type: 字符串处理 简单题
	
	date : 2005.4.23 北师大校内比赛

Source 
*/
#include<stdio.h>
#include<string.h>
#include<math.h>

void main()
{
	int i,j,k;
	int n;
	int len,row;
	char a[300]={0};
	char matrix[100][100]={0};
	

	while(1)
	{

		memset(matrix,0,sizeof(matrix));
		memset(a,0,sizeof(a));	
		scanf("%d",&n);
		if(n==0) break;

		scanf("%s",a);
		len=strlen(a);
		
		if(row%n==0)
			row=len/n;
		else
			row=len/n+1;


		 k=0;

		for(i=0;i<row;i++)

		{//	printf("%d",i);
		
			
			if(i%2==0)
			{
				for(j=0;j<n;j++)	
				{
						matrix[i][j]=a[k++];
				
				}//printf("%d ",a[35]);

			}
			else
			{
				for(j=n-1;j>=0;j--)
	
	
				{
						matrix[i][j]=a[k++];
				
				}//printf("%d ",a[35]);


			}


		}
		for(i=0;i<n;i++)
		{
			for(j=0;j<row;j++)
			{
				if(matrix[j][i]!=0)
					printf("%c",matrix[j][i]);
			}
		}
		printf("\n");

		


	}
		



}

